1. Field of the Invention
The present invention relates to a character processing apparatus and, more particularly, to an electronic typewriter in which recorded characters or the like can be deleted on a word unit basis.
2. Related Background Art
A conventional electronic typewriter has a printing apparatus and a keyboard input apparatus. The keyboard input apparatus has various kinds of function keys such as character input keys, a space key and a back space key to feed a printer head to the right and left in the horizontal direction, a return key, an index key, and a reverse index key to feed a recording paper upward and downward in the vertical direction, and a delete key to delete recorded characters or the like when they were erroneously input or the like, etc.
On the other hand, in recent years, the electronic typewriter has been electronized more and more. There has been provided an electronic typewriter having a back trace function in which, by storing recorded characters or the like into memory means such a memory or the like, a printer head is returned to a plurality of preceding lines of the recorded characters or the like on a character or word unit basis. Further, there has been provided an electronic typewriter having a word delete function in which characters or the like recorded in the same line are deleted on a word unit basis.
In such an electronic typewriter, the operator makes a desired document or the like by operating the keyboard.
For instance, to make a sentence as shown in FIG. 13A, the key input operations are executed in accordance with an order as shown in FIG. 13B.
In FIG. 13B, SP denotes a space key and RTN indicates a return key. By inputting the return key, a recording paper is fed by a predetermined amount and the printer head is moved to the position of y in FIG. 13A.
It is now assumed that the operator becomes aware of a mistake of the input of the words shown by a region x in the diagram and tries to correct "TYPEWRTER." to "TYPEWRITER.".
The first method of correction is shown in FIG. 14A. First, the printer head is moved from y to y' in FIG. 13A by returning the recording paper by a predetermined amount by performing the reverse index key input (RIX). Next, by executing the space key printer head is moved from y' to z in FIG. 13 By executing the delete key input (DEL) four times, the recorded characters are deleted in accordance with the order of ".", "R", "E", and "T". The character key input is then executed in accordance with the order of "I", "T", "E", "R", and "." so as to obtain the correct word spelling. In this manner, the correction is executed.
The second method is shown in FIG. 14B and is applied to an apparatus having the back trace function mentioned above. First, the printer head is moved from y to z in FIG. 13A by performing the back trace key input (BTR). The recorded characters ".", "R", "E", and "T" are deleted by executing the delete key input (DEL) four times in a manner similar to the above. Then, characters "I", "T", "E", "R", and "." are retyped. In this manner, the correction operation is executed.
The third method is shown in FIG. 14C and is applied to the case of an apparatus having the word delete function mentioned above. In a manner similar to the above, the printer head is moved to z in FIG. 13A by performing the back trace key input (BTR). "TYPEWRTER." are all deleted by executing the word delete key input (WDEL) and "TYPEWRITER." are retyped. In this manner, the correction is executed.
However, when comparing the number of key input times which are required to correct the sentence shown in the example, there is a drawback such that in the case of the first method, its value becomes a maximum and the operations are complicated. According to the second method using the back trace function as an improvement of the first method, although the operation to move the printer head to the deletion start position z is simplified, the number of key input operations which are required to delete a portion of a word is the same as that in the first method. In addition, as in the example, in order to change "TYPEWRTER." to "TYPEWRITER.", the operator must count the position where he wants to input "I", so that there is the drawback that an erroneous operation such that too many or the wrong recorded characters can be deleted.
The third method using the word delete function has been considered as an improvement on such methods. However, although the operability with respect to the deletion of the recorded characters is improved, all of the words are deleted by a single operation. Therefore, in the example, the portion of "TYPEWR" in "TYPEWRTER." is additionally deleted, so that "TYPEWR" must be again input and there is a drawback that the number of key input operations which are required for correction is larger than that in the second method.
On the other hand, according to the third method, since the number of deleting operations of the recorded characters is large, the operating time which is required for deletion, the amount of deleting ribbon used, the amount of a recording ribbon used when retyping, and the like increase. Thus, there are drawbacks such that the correcting time (throughput) increases and the running cost also increases.
In addition, even in any of the conventional methods mentioned above, in spite of the fact that the operator wants to correct the words which have just previously been recorded, he needs to execute other operations of the reverse index key (RIX), the space key (SP), the back track key (BTR), and the like which are not directly concerned with the deleting operation. Consequently, there is a drawback such that the correcting operation cannot be easily understood.